Method for preventing plant growth



United States Patent 3,340,043 METHOD FOR PREVENTING PLANT GROWTH JohnF. Olin, Ballwin, Mo., assignor to Monsanto Company, a corporation ofDelaware No Drawing. Original application Aug. 28, 1961, Ser. No.134,159. Divided and this application June 14, 1963, Ser. No. 293,555

5 Claims. (Cl. 71-118) This application is a division of applicationSer. No. 134,159, filed Aug. 28, 1961, now abandoned.

This invention relates to the control of plant systems, includinggerminating seeds and emerging seedlings. In one aspect, this inventionrelates to valuable herbicidal compositions. In another aspect, thisinvention relates to methods for destroying undesirable plant vegetationwithout substantially alfecting desirable plant vegetation. In anotheraspect, this invention relates to methods for preventing the germinationof seeds of'undesirable plants and for preventing the growth of emergingseedlings of said plants. In another aspect, this invention relates tocertain solely ortho-substituted a-haloacetanilides as new compounds. v

In recent years, the use of chemicals for affecting plant systems hasfound wide-spread acceptance among agriculturalists. For example,chemical compositions have been applied to fully developed vegetation todestroy the same in either a selective or non-selective manner. It isrelatively easy to destroy the aerial portion of developed vegetationbecause the vegetation is brought into direct contact with the.herbicide composition; however, it is sometimes more difficult toachieve a lethal aifect on germinating seeds lying in the soil andseedlings emerging from the soil. Destruction of germinating seeds andemerging seedlings is important in preventing regrowth from the plantsafter the herbicide composition has either been washed away by rainfallor dissipated by otheractions. Unfortunately, it is usually necessary touse an excessive amount of the herbicidal composition in order to affectthe germinating seeds and emerging seedlings and thereby achievelong-lasting plant control. The extended control of plant life duringthe growth of desirable plants is very often involved in preventing thegrowth of certain undesirable grasses ,and'weeds, such as crab grass andfoxtail. Obviously, a more bountiful growth of desirable grasses andcrop plants will result if growth of these undesirable weeds and grassesis prevented before the soil is depleted of moisture and nutrients.

Very useful herbicidal compositions containing certainnuclear-substituted and nitrogen-substituted a-haloacetanilides aredisclosed and claimed in US. Patent 2,863,752, issued to Hamm andSpeziale. They discovered that the a-haloacetanilides required in alkylsubstitutents of up to 6 carbon atoms on the amide nitrogen atom and analkyl substituent of up to 4 carbon atoms on the aromatic ring in orderto produce herbicidal activity. Even though these a-haloacetanilides ofHamm and Speziale are very effective herbicides, it is desirable in manscontinued battle with undesirable plant life to improve theeffectiveness of these herbicidal compositions.

-I have now discovered, much to my surprise, that the unit activity ofan u-haloacetanilide with respect to broadleaf plants is decreased incomparison to the unit activity with respect to grass plants bysubstituting only a single alkyl radical, limited to a tertiary alkylradical, on the aromatic ring in only the ortho position with respect tothe amide nitrogen atom, and not substituting any other substituents oneither the aromatic ring or the amide nitrogen atom. Thus, the newlydiscovered a-haloacetanilides are more selective in preventing thegrowth of grass plants than broadleaf plants. I

An object of this invention is to provide novel herbicidal compositionscontaining as an-essential ingredient an a-haloacetanilide having asingle tertiary alkyl substituents substituted on the aromatic ringinthe ortho posi-- tion with respect to the amide nitrogen atom. 7

.Another object of this invention is to provide novel herbicidalcompositions having high unit .activity for certain plant species.

Another object of this invention is to provide novel' herbicidalcompositions which exhibit selectivity in'affecting certain undesirableplant systems without affecting desirable plant systems.

, Another objectof this invention is to provide methods for thesuppression and control of undesirable vegetation growing inter-mingledwith desirable vegetation.

Another object of this invention is to provide methods for preventingthe germination of seeds of undesirable plants and for preventing thegrowth of undesirable seeds of Other aspects, objects, and advantages ofthis inven-.

tion will be apparent from a consideration of the accompanyingdisclosure and the appended claims.

According to the present invention, there are provided herbicidalconcentrate compositions'comprising an herbi-- cide adjuvant and ana-haloacetanilide ofthe formula wherein R is a tertiary alkylradical'having at least 4 carbon atoms and X is anhalogen atom selectedfrom' the group consisting of chlorine, bromine, and iodine.-

Also, according to the present invention, there are provided herbicidalcompositions comprising- 21 carrier, an herbicide adjuvant .and a toxic.or growth-inhibiting amount of an d-haloacetanilide of the formula asdescribed above. 1 I i Also, according to the present invention, thereare provided methods for affecting plant systems, i.e., germinatingseeds and emerging plant'seedlings, in a manner to prevent the growth ofsaid seeds and said emerging seedlings and destroy the same by theapplication of a toxic or growth-inhibiting amount of anu-haloacetanilide of th formula as described above.

Further, according to the present invention, there are substituent, R inthe formula above, is a tertiary alkyl radical having at least 4 carbonatoms and, preferably, not more than 10 carbon atoms. This tertiaryalkyl radical may also have further chain branching. Examples of somesuitable tertiary alkyl radicals include: tert-butyl, tertamyl,1,1,2-trirnethylpropyl, 1,1-dimethylbutyl, 1,1-dimethylamyl,1,1,2-trimethylbutyl, 1,1,3-trimethylbutyl, 1, 1,3,3-tetramethylbutyl,l,1,2,3-tetramethylbutyl, 1,1,2,2- tetramethylbutyl and1,1-dimethyloctyl groups.

The halogensubstituent on the a-carbon atom of the haloacetanilide,identified by X in the formula above,

- may be either a chlorine, bromine, or iodine atom.

. Patented Sept. 5,196.7

The u-haloacetanilides of this invention may in general be prepared byhaloacetylation of suitable ortho-substituted aromatic amines, which maybe prepared for example, by the process disclosed in application S.N.824,- 455, filed July 2, 1959 now abandoned, from a primary aromaticamine and a branch-chain olefin. The haloacetylating agent is preferablyeither a haloacetic anhydride, such as chloroacetic anhydride, or ahaloacetyl halide, such as chloroacetyl chloride, bromoacetyl bromide,or the like.

The haloacetylation reaction is preferably conducted in the presence ofa suitable liquid reaction medium. The liquid reaction medium must beanhydrous if the acetylating agent is a haloacetic anhydride; however,either anhydrous reaction mediums or mediums cotnaining water can beused with haloacetyl halide acetylating agents. Examples of somesuitable reaction mediums for use with either acetylating agent includebenzene, diethyl ether, hexane, methylethyl ketone, chlorobenzene,toluene, chloroform, and the xylenes. Since an acid or hydrogen halideis eliminated in the haloacetylation reaction, it is also desirable tohave an acid acceptor present in the reaction zone to neutralize theacid formed. Suitable acid acceptors for anhydrous solvent systems,include the orthosubstituted aromatic amine reactants, which may bepresent in the reaction zone in an amount greater than that required forthe acetylation, tertiary amines, and pyridine. Acid acceptors inaqueous solvent systems include alkali or alkaline earth hydroxides andalkali or alkaline earth metal carbonates or bicarbonates.

The haloacetylation reaction is generally carried out at a temperaturewhich is below room temperature, preferably in the range of from C. to15 C. It is not usually desirable to carry out the reaction at atemperature above room temperature because hydrolysis of the haloacetylhalide takes place and the reaction rate is excessively high. It isgenerally preferable to carry out the reaction at atmospheric pressurealthough sub-atmospheric pressure and super-atmospheric pressure can beused. Although the haloacetylation reaction can be carried out usingstoichiometric amounts of reactants, it is usually preferable to usefrom 2 to 5% of an excess of the acetylating agent. The acetanilideproducts may be sepaarted from the reaction mixture by methods wellknown to those skilled in the art, such as by distillation or byfractional crystallization from the reaction medium or from solvents incase the desired product is a soluble substance.

The advantages, desirability and usefulness of the present invention areillustrated by the following examples.

Example 1 In this example, 2-tert-butyl-2-chloroacetanilide was preparedby reacting 30 g. (0.2 mole) of Z-tert-butylaniline dissolved in 100 ml.of hexane with 58 ml. of a 40% solution of chloroacetic anhydride. Thereaction was exothermic and minutes after the addition of thechloroacetic anhydride was completed, 100 ml. of water was added. Thesolvents were removed by evaporation of the reaction mixture overnight.The residue obtained was filtered and the filter cake washed severaltimes with water. The filter cake was dissolved in 75% methanol andcrystallization of the 2'-tert-butyl-2-chloroacetanilide effected bycooling. After washing the product with cold methanol and drying, g. ofthe product was obtained having a melting point of 97.97" C. Analysis ofthe product was found to be 15.72% chlorine as compared with thecalculated value of 15.78% chlorine. The proposed structure for theproduct was confirmed by inspection of the in frared spectrum.

Example 2 In this example, 2-chloro-2-(1,1-dimethylpropyl)acetanilidewas prepared by reacting 16.3 g. (0.1 mole) of 2-(1,1-dimethylpropyl)aniline dissolved in 100 ml. of heptane with ml. ofchloroacetic anhydride in chloroform. The reaction was exothermic andadditional heating was unnecessary. After the reaction had subsided, thereaction mixture was washed with water and evapoarted to remove theheptane solvent. The residue obtained was dissolved in methanol, dilutedwith water, and placed in an ice-box to effect crystallization of 18 g.of flesh-colored crystals having a melting point of 7171.6 C. andidentified as 2-chloro-2'-(1,l-dimethylpropyl)acetanilide.

Example 3 In this example, 2-bromo-2'-tert-butylacetanilide was preparedby reacting 29.8 g. (0.2 mole) of Z-tert-butylaniline dissolved in 250g. of anhydrous benzene with 40.4 g. (0.2 mole) of bromoacetyl bromide.The bromo acetyl bromide was added with stirring to theZ-tert-butylaniline solution, which also contained 20 g. of pyridine,over a period of 10 minutes with the temperature of the reaction mixturerising to 65 C. After the addition of the bromoacetyl bromide wascompleted, the reaction mixture was stirred for an additional 10 minutesand the product washed twice with water. After evaporating the solventsunder a hood, the 2-bromo-2-tert-butylacetanilide was crystallized fromdilute methanol as fine tan needles. Upon recrystallization frommethanol, 30.5 g. of the product was obtained having a melting point of112.8- 113.4 C.

Example 4 In this example, 2-chloro-2'-(1,1-dimethylbutyl)acetanilideprepared by reacting 89.4 g. (0.5 mole) of 2-(1,1- dimethylbutyDaniline,dissolved in 200 ml. of benzene with g. of chloroacetic anhydride inchloroform. The chloroacetic anhydride solution was added over a periodof 1-0 minutes followed by gentle heating of the reaction mixture for 15minutes. Thereafter, 250 ml. of water was added to the reaction mixtureand the solvents removed by distillation. Upon sitting all night, theproduct became solid. The water was removed by decantation and the solidmaterial washed once with water and dissolved in 500 ml. of hotmethanol. The mixture obtained was filtered and the filtrate dilutedwith water. Crystallization of the 2chloro-2-(1,1-dirnethylbutyl)acetanilide was effected in an ice-box.After washing the product with 80% cold methanol solution and drying, g.of the product was obtained having a melting point of 75.2- 76 C.Analysis of the product was found to be 13.77% chlorine as compared withthe calculated value of 13.97% chlorine.

Example 5 In this example, 2'-tert-butyl-2-iodoacetanilide was preparedby reacting 75 g. (0.5 mole) of Z-tert-butylanaline dissolved in 400 ml.of benzene with 88 g. (0.43 mole) of iodoacetyl chloride. The iodoacetylchloride was added to the Z-tert-butylaniline solution, which alsocontained 50 g. of pyridine, with the formation of a vigorous reaction.After permitting the reaction mixture to set for 10 minutes, 500 m1. ofa warm 2% sodium thiosulfate solution was added to form 3 layers. Theupper or benzene layer was decanted, washed with water, filtered, andevaporated in the hood. The dark colored residue obtained was heatedwith heptane. The dark brown colored material was separated from theheptane solution by decantation. The heptane layer was filtered hot andcrystallization effected by cooling. The product obtained wasrecrystallized from dilute methanol to obtain the 2-tert-butyl-2-iodoacetanilide as tan cystals having a melting point of97.598 C.

Example 6 In this example, the pre-emergent herbicidal ratings of someof the ortho-substituted a-haloacetanilides of this invention weredetermined in greenhouse tests in which a specific number of seeds of 12different plants, each respresenting a rincipal botanical type, wereplanted in greenhouse flats. A good grade of top soil was placed ineither 9 /2" x 5%" x 2%" or 9" x 13" x 2" aluminum pans and compacted toa depth of inch from the top of the pan. On top of the soil were placedfive seeds of each of radish, morning glory, and tomato; seeds of eachof sugar beet, sorghum, and brome grass; seeds of each of wildbuckwheat, giant foxtail, rye grass, and Wild oat; approximately 20 to30 (a volume measure) of each of pigweed and crab grass; and either 2 or3 seeds of soybean. Two different type plantings were made; one whereinthe herbicidal composition was applied to the surface of the soil andthe other wherein the composition was admixed with or incorporated inthe top layer of soil. In the surface-application plantings, the seedswere arranged with 3 soybean seeds across the center of the largealuminum pan, the monocotyledon or grass seeds scattered randomly overone-third of the soil surface, and the diocotyledon or broadleaf seedsscattered randomly over the remaining one-third of the soil surface atthe other end of the pan. The seeds were then covered with inch ofprepared soil mixture and the pan leveled. In the soil-incorporationplantings, 450 g. of prepared soil mixture was blended with theherbicide composition in a separate mixing container for covering theseeds which were planted in the smaller of the two aluminum pans. Theseeds in this planting were arranged with a soybean seed planted indiagonal corners and the monocotyledon seeds and the dicotyledon seedseach scattered randomly over one-half of the soil surface. Theherbicide-incorporated soil mixture was used to cover the seeds. Theherbicide composition was applied in the surface-application plantingprior to the watering of the seeds. This application of the herbicidecomposition was made by spraying the surface of the soil with an acetonesolution containing a sufiicient quantity of the candidate chemical toobtain the desired rate per acre on the soil surface. The watering ofthe seeds in both type plantings was accomplished by placing thealuminum pans in a sand bench having /2 inch depth of water thereon andpermitting the soil in the pans to absorb moisture through theperforated bottom of the pans.

The planted pans were thereafter placed on a wet sand bench in agreenhouse and maintained there for 14 days under ordinary conditions ofsunlight and watering. At the end of this time, the plants were observedand the results recorded by counting the number of plants of each 6CMorning glory D-Wild oats EBrome grass FRye grass GRadish HSugar beetIFoxtail JCrab grass KPigweed L-Soybean MWild buckwheat N--TomatoO-Sorghum Individual injury ratings for each plant type are reported inTable I. In addition, the total injury rating for all grass plants andthe total injury rating for all broadleaf plants are also reported inTable I. For grasses, the maximum total is 18 for the 6 grass plants'atratings of 3. For broadleafs, the maximum total is 21 for the 7broadleaf plants at ratings of 3.

The data in Table I illustrate primarily the selective herbicidalactivity but also the general herbicidal activity of some of theortho-substituted a-haloacetanilides of this invention. It will be notedthat haloacetanilides substituted with a tertiary alkyl group ortho tothe amide nitrogen atom and no other substitution demonstrate veryoutstanding selective herbicidal activity. It will also be noted fromthe data in Table I that general herbicidal activity can be obtained athigher levels of application. The grass specificity is achieved atfairly low application rates, for example, at rates as low as 5 lbs/acreso that very economical treatment is possible. The three botanical typesor genera of grasses effectively controlled by the ortho-substituteda-haloacetanilides of thi invention embrace a large number ofundesirable plants, or weeds, frequently found in vegetable crops. Butthese a-haloacetanilides are not limited to removing grasses frombroadleaf plants since the selective action is such that certain generaof grasses can be removed from corn, which is also a genus of grass.These a-haloacetanilides rotundus and Cyperus esculentus.

TABLE I.PRE-EMERGENCE HERBICIDAL ACTIVITY OF THE ORTHO-SUBSIITUTEDa-HALOAOENTANILIDES [Surface application] Plant type Total Injury ratingCompound Rate,

1b./acre A B C D E F G H I J I K 1 L M N I 0 Grass Broadleat2-tertbuty1-2-chloroacetauilide 5 3 1 1 s 3 s 0 2 s a 2 0 0 2 a 18 72-ehloro-2-(l,l-dimethylpropyl)acetauilide g g g g g g g g 8 a g g2-bromo-2-tert-buty1acetanilide g i g 8 3 3 8 g g g 6 g 8 g 12-tert-butyl-24odoacetanilide g g 8 g 3 g g i g g g 8 g 5 g2-chl0ro-2-(1,l-dimethylbutyl) acetanilide 5 2 1 0 1 0 2 0 2 3 3 3 1 0'0 2 11 6 species which germinated and grew. The herbicidal ratingExample 7 was obtained by means of a fixed scale based on the averagepercent germination of each seed lot. The herbicidal ratings are definedas follows:

0-No phytotoxicity 1Slight phytotoxicity 2-Moderate phytotoxicity3Severe phytotoxicity AGeneral grass BGeneral broadleaf In thefirstcomparison reported in Table II, the critical nature of thepositioning of the tertiary alkyl group on the aromatic ring is veryeffectively demonstrated. Thus, a general grass rating of 3 and ageneral broadleaf rating of 1 was obtained at an application rate of 5lbs./ acre for a chloroacetanilide of this invention having a tert-butylgroup located in the ortho position with respect to the amide nitrogenatom whereas no herbicidal activity was observed at an application rateof 25 lbs/acre, an application rate 5 times greater than the applicationrate of the compound of this invention, for an acetanilide having atert-butyl group located in the para position instead of the orthoposition with respect to the amide nitrogen atom. It will be appreciatedin this comparison that the alkyl substituents are exactly the same, theonly difference in the respective a-chloroacetanilides being in thelocation of these alkyl groups with respect to the amide nitrogen atom.

TABLE II.-COMPARISON OF PRE-EMERGENCE HERBICIDAL ACTIVITY OF VARIOUSa-HALOACETANILIDES Plant Type Total Injury Rating Compound Comments A BC D E F G H I J K L M I N I Grass Broadleaf2-tert-butyl-Zchloroaeetanilide 3 1 1 3 3 3 0 2 3 3 2 0 0 2 3 18 7 Atlb./acre. 4-tert-butyl-2-chloroacetanilide 0 0 0 0 0 0 0 0 0 0 0 0 0 0 00 0 At lbJacre. 2-tert-butyl-2-chloroacetanilide 3 1 1 3 3 3 0 2 3 3 2 0O 2 3 18 7 At 5 lb./a.cre. 2-chloro2-isopropylacetanilide-. O 0 0 0 1 00 0 0 2 0 0 0 0 0 3 0 Do. 2-tert-butyl-2chloroacetanilide 3 1 1 3 3 3 02 3 3 2 0 0 2 3 18 7 At 5 lbJacrc. Z-tert-butylacetanilide 0 0 O 0 0 0 00 0 0 0 0 0 O 0 O 0 At 25 lbJacre. 2-tcrt-butyl-2-chloroacetanilide 3 11 3 3 3 0 2 3 3 2 0 0 2 3 l8 7 At 5 lb./acre.2-tert-butyl-2,2-dichloroacetanilide 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0At 25 lbJacre. 2'-tert-butyl-2,2,2trichloroacetanilide 0 0 0 0 0 0 0 0 00 0 0 0 0 0 0 0 Do. 2 tert-hutyl-2-chloroacetanilide 3 1 1 3 3 3 0 2 3 32 0 0 2 3 18 7 At 5 lb./acre. 2,N-di-tert-butyl-2-chloroacetauilide 0 00 0 0 0 0 0 0 0 0 0 O 0 0 O 0 Do. 2'-tert-butyl-.b-iodoacetanilide 3 0 02 3 3 0 1 3 3 3 0 0 0 3 17 4 Do, N-tert-butyl-2-io doacetanilide 0 0 0 00 0 0 0 0 0 2 0 0 0 0 O 2 D0.

The necessity for a tertiary alkyl group instead of a formulation aidsor conditioning agents permitting the secondary alkyl group in the orthoposition with respect to the amide nitrogen atom is demonstrated in thesecond comparison reported in Table II. In this comparison achloroacetanilide having a tert-butyl group substituted in the orthoposition was compared with an a-OhlOI'O- acetanilide having an isopropylgroup substituted in the same position. At the application rate of 5lbs/acre, a general grass rating of 3 and a broadleaf rating of 1 wasobtained for the compound having the tert-butyl substituent whereasalmost no phytotoxicity was observed for the compound having theisopropyl substituent.

The third comparison in Table H demonstrates the effect of removing thechloro group from the a-haloacetanilide. No phytotoxicity was observedwith the nonhalogenated compound at any rate of application, not even atthe extremely heavy rate of 25 lbs./ acre.

Since the previous comparison demonstrates the necessity for a halogensubstituent, the next comparison in Table II was arranged to determinethe effect of diand tri-substitution of halogen groups. Surprisingly,neither the di-chloro nor the tri-chloro derivatives demonstrated anyherbicidal activity at the heavy rate of 25 lbs./ acre. Therefore, onlythe monohalo derivative is active as a herbicide.

In the next comparison reported in Table II, a tertiary alkyl group wassubstituted on the amide nitrogen atom in addition to the tertiary alkylgroup substituted in the ortho position on the aromatic ring as in theacetanilides of this invention. Thus, the substitution of a tertiarybutyl group on the amide nitrogen atom of the 2'-tert-butyl-2-chloroacetanilide of this invention resulted in the complete destructionof the herbicidal activity of the acetanilide of this invention at anapplication rate of 5 lbs./ acre.

The last comparison reported in Table II demonstrates that the tertiaryalkyl group may not be removed from the aromatic ring and substituted onthe amide nitrogen atom. As reported, an a-iodoacetanilide having asingle tert-butyl substituent on the amide nitrogen atom has almost noherbicidal activity at an application rate of 5 lbs./ acre whereas thecorresponding a-iodoacetanilide having a tert-butyl group located on thearomatic ring in the ortho position has very severe phytotoxicity at thesame rate of application.

The data in this example very clearly demonstrate the critical effect ofnot only the nature of the alkyl substituent but also its location withrespect to the nitrogen concentrate composition to be readily mixed witha suitable solid or liquid carrier in the field for application of theactive ingredient on soil or plant surfaces in a toxic concentration ina form which enables prompt assimilation by the germinating seeds,emerging seedlings, or full grown plants. Thus, the herbicidalcompositions of this invention include not only the concentratecompositions comprising the active ingredient and the herbicidaladjuvant but also herbicidal toxicant compositions applied in the fieldcomprising the concentrate composition (i.e., active ingredient plusherbicidal adjuvant) and the carrier.

Herbicidal adjuvants useful in preparing the concentrate compositionsand, therefore, the herbicidal toxicant compositions applied to the soilor plants, include particulate solid or liquid extending agents such assolvents or diluents within which the active ingredient is dissolved orsuspended, wetting or emulsifying agents which serve in providinguniform dispersions or solutions of the active ingredient in theextending agents, and adhesive agents or spreading agents which improvethe contact of the active ingredient with the soil or plant surfaces.All herbicidal compositions of this invention include at least one ofthe above types of herbicidal adjuvants and usually include an extendingagent and a wetting or emulsifying agent because of the nature of thephysical properties of the ot-haloacetanilides of this invention.

In general, the u-haloacetanilides of this invention are insoluble inwater and are not readily soluble in many organic solvents. Therefore,the choice of a liquid extending agent is somewhat limited if it isdesired that the active ingredient be in solution in the extendingagent. The active ingredient need not be dissolved in the extendingagent but may merely be dispersed or suspended in the extending agent asa suspension or emulsion. Also, the a-haloacetanilides may first bedissolved in a suitable organic solvent and the organic solution of theactive ingredient then incorporated in water or an aqueous extendingagent to form a heterogenous dispersion. Examples of some suitableorganic solvents for use as extending agents include hexane, benzene,toluene, acetone, cyclohexanone, methylethylketone, isopropanol,butanediol, methanol, diacetone alcohol, xylene, dioxane, isopropyl Iether, ethylene dichloride, tetrachloroethane, hydrogenated naphthalene,solvent naphtha, petroleum fractions (e.g., those boiling almostentirely under 400 F. at atmospheric pressure and having flash pointsabove about 80 F., particularly kerosene), and the like. Where truesolutions are desired, mixtures of organic solvents have been found tobe useful, for example, 1:1 and 1:2 mixtures of xylene andcyclohexanone.

Solid extending agents in the form of particulate solids are very usefulin the practice of the present invention because of the low solubilityproperties of the u-haloacetanilides of this invention. In using thistype of extending agent, the active ingredient is either adsorbed ordispersed on or in the finely-divided solid material. Preferably thesolid extending agents are not hygroscopic but are materials whichrender the composition permanently dry and free flowing. Suitable solidextending agents include the natural clays, such as china clays, thebentonites and the attapulgites; other minerals in natural state, suchas talc, pyrophyllite, quartz diatomaceous earth, fullers earth, chalk,rock phosphate, kaolin, kiselghur, volcanic ash, salt, and sulfur; thechemically modified minerals, such as acid-washing bentonite,precipitated calcium phosphate, precipitated calcium carbonate, calcinedmagnesia, and colloidal silica; and other solid materials such aspowdered cork, powdered wood, and powdered pecan or walnut shells. Thesematerials are used in finely-divided form, at least in a size range of20-40 mesh and preferably in much finer size.

The particulate solid concentrate compositions are applied to the soilby admixture at the time of application with a particulate solid carriermaterial. If desired, this concentrate composition can also be appliedas a wettable powder using a liquid carrier material. When used by thismethod, a wetting agent or surface active agent is added to theconcentrate composition in order to render the particulate solidextending agent wettable by water to obtain a stable aqueous dispersionor suspension suitable for use as a spray. Also, the extending agentapplied as a wettable powder is used in very finely-divided form,preferably in a size as small as 100 mesh or smaller.

The surface active agent, that is the wetting, emulsifying, ordispersing agent, used in the herbicidal composition of this inventionto serve in providing uniform dispersions of all formulation componentsof both liquid and dust types in both the concentrate compositions andthe toxicant compositions applied, may be either anionic, cathionic, ornon-ionic types, including mixtures thereof. Suitable surface activeagents are the organic surface active agents capable of lowering thesurface tension of water and include the conventional soaps, such as thewater-soluble salts of long-chain carboxylic acids; the amino soaps,such as the amine salts of long-chain carboxylic acids; the sulfonatedanimal, vegetable, and mineral oils; quaternary salts of high molecularweight acids; rosin soaps, such as salts of abietic acid; sulfuric acidsalts of high molecular weight organic compounds; algin soaps; ethyleneoxide condensated with fattyacids, alkyl phenols and mercaptans; andother simple and polymeric compositions having both hydrophilic andhydrophobic functions.

The herbicidal concentrate compositions of this invention ordinarilyhave the active ingredient and the surface active agent present inhigher concentrations than the toxicant compositions applied in thefield so that upon dilution with the liquid or solid carrier,compositions containing optimum proportions of active ingredient andsurface active agent are prepared to obtain uniform distribution and tomaintain the active ingredient in a form which enables the promptassimilation by the plant.

The liquid concentrate compositions of this invention preferablycomprise 5% to 95% by weigh-t of the active ingredient and the remainderthe herbicidal adjuvant, which may be solely liquid extending agent orsurface active agent (including adhesive agent), but preferably is acombination of liquid extending agent and surface active agent.Preferably, the surface active agent comprises from 0.1% to 15% byweight of the total concentrate compositions. The remainder of thecomposition is the liquid extending agent.

Use of the surface active agent is necessary in the formulation ofliquid concentrate compositions in order to obtain a compositioncontaining a sufficient concentration of the difficulty solublea-haloacetanilide in the liquid extending agent. However, the liquidextending agent must be selected not only on the basis of the amount ofthe a-haloacetanilide dissolved but also upon the basis of the solutiontemperature of the total composition. Thus, in some formulations, aparticular combination of solvents give a sufficiently low solventtemperature but the amount of the u-haloacetanilide dissolved ordispersed in the mixture is insufficient and a suitable surface activeagent must be selected in order that more a-haloacetanilide can bedispersed in the composition. Preferably, the concentrate compositionhas a solution temperature below 0 C. although compositions havingsolution temperatures as high as 20 C. can be used.

The concentration of m-haloacetanilide in the particulate solid or dustconcentrate composition of this invention may vary over wide rangesdepending upon the nature of the solid extending agent and the intendeduse of the composition. Since the a-halo acetanilides of this inventionhave very high toxicities and are applied at very low rates, theconcentration of the active ingredient in the dust composition may bevery low and may comprise as little as 1% or less by weight of the totaldust composition; however, a concentration in the range of 5% to 98% byweight of the total composition is preferred. The remainder of thecomposition is the herbicidal adjuvant which is usually only theparticulate solid extending agent. Thus, the surface active agent is notusually required in dust concentrate compositions although it can beused if desired. However, if the dust concentrate composition is to beapplied as a wettable powder, surface active agent must be added to theconcentrate composition and ordinarily the amount of surface activeagent will be in the range of 0.1% to 15% by weight of the composition.

The carrier material, used for the uniform distribution of thea-haloacetanilide in an herbicidally effective amount to inhibit thegrowth of either all or selected plants, may be either a liquid or aparticulate solid material. The liquid and solid extending agents usedto prepare the concentrate composition may also be used as the carrier;however, the use of these materials as a carrier is often noteconomical. Therefore, water is the preferred liquid carrier, both foruse with the liquid concentrate composition and the wettable powderconcentrate. Suitable particulate solid carriers include the particulateextending agents noted above as Well as the solid fertilizers such asammonium nitrate, urea, and superphosphate, as well as other materialsin which plant organisms may take root and grow, such as compost,manure, humus, sand and the like.

The liquid and dust concentrate compositions of this invention can alsocontain other additaments such as fertilizer and pesticides. Also, theseadditaments may be used as, or in combination with, the carriermaterials.

The herbicidal compositions of this invention are applied to the plantsystems in the conventional manner. Thus, the dust and liquidcompositions may be applied to emerging seedlings by the use ofpower-dusters, broom, and hand sprayers, and spray-dusters. Thecompositions can also be very suitably applied from airplanes as a dustor a spray because the herbicidal compositions of this-invention areeffective in very low dosages. In preventing growth of germinating seedsor emerging seedhugs, the dust and liquid com-positions are applied tothe soil according to conventional methods, and, preferably, distributedin the soil to a depth of at least /2 -inch below the soil surface. Itis not absolutely necessary that the herbicidal compositions be admixedwith the soil particles and these compositions can be applied merely byspraying ,or sprinkling on to the surface of the soil.

The herbicidal compositions of this invention can also be applied byaddition to irrigation water supplied to the field to be treated. Thismethod of application permits the penetration of the compositions intothe soil as the water is absorbed therein. Dust compositions sprinkledon the surface of the soil can be distributed below the surface of thesoil by the usual discing, dragging, or mixing operations.

The application of a growth-inhibiting amount or toxic amount of thea-haloacetanilide to the plant system is essential in the practice ofthe present invention. The exact dosage to be applied is dependent notonly upon the specific whaloacetanilide but also upon the particularplant species to be controlled and the stage of growth thereof as wellas the part of the plant to be contacted with the toxicant. Theseherbicidal compositions are usually applied at a rate in the range of 1to 25 lbs. per acre or higher. It is believed that one skilled in theart can readily determine from this disclosure, including the examples,the optimum rate to be applied in any particular case.

Although the active ingredient in the herbicidal compositions of thisinvention is preferably an ortho-substituted u-haloacetanilide asdescribed in this specification, other a-haloacetanilides having nuclearalkyl substitution and/ or halo substitution in other than the orthopositions and/or having amide nitrogen substitution may also be presentin the herbicidal compositions and contribute to the activity of thecomposition. However, the essential active ingredient of the herbicidalcompositions of this invention is the ortho-substitutedu-haloacetanilide disclosed in this specification. Of course, oneskilled in the art will understand that mixtures of variousortho-substituted a-haloacetanilides can also be used.

Reasonable variation and modification of the invention as described arepossible, the essence of which is that there have been provided (1)herbicidal concentrate compositions comprising an herbicidal adjuvantand, as an essential active ingredient, an ortho-substitutedu-haloacetanilide, (2) herbicidal toxicant compositions comprising anherbicidal adjuvant, a carrier, and, as an essential active ingredient,a toxic or growth-inhibiting amount of an ortho-substituteda-haloacetanilide, (3) methods for suppression and control ofundesirable vegetation, such as germinating seeds and emergingseedlings, by the application of an ortho-substituted a-haloacetanilidethereto, and (4) certain ortho-substituted a-haloacetanilides as newcompounds.

I claim:

1. A method for preventing plant growth which comprises applying tosoils normally supporting said growth a growth-inhibiting amount of ana-haloacetanilide of the formula ll IITH-C-CHzX wherein R is tertiaryalkyl having at least 4 carbon atoms and X is an halogen atom selectedfrom the group consisting of chlorine, bromine, and iodine.

2. A method for preventing the undesirable growth of plants whichcomprises distributing on the surface of soil containing seeds of saidplants a growth-inhibiting amount of an a-haloacetanilide of the formulall IIIH-O-CHaX wherein R is tertiary alkyl having at least 4 carbonatoms, and X is a halogen atom selected from the group consisting ofchlorine, bromine, and iodine.

4. A method for preventing the undesirable growth of plants whichcomprises contacting the seeds of said plants positioned in the soilwith a growth-inhibiting amount of an et-haloacetanilide of the formulaII IITH-O-OHzX wherein R is tertiary alkyl having at least 4 carbonatoms and X is an halogen atom selected from the group consisting ofchlorine, bromine, and iodine.

5. A method for preventing the undesirable growth of plants whichcomprises impregnating the soil with a growth-inhibiting amount of anot-haloacetanilide of the formula wherein R is tertiary alkyl having atleast 4 carbon atoms and X is an halogen atom selected from the groupconsisting of chlorine, bromine, and iodine.

References Cited UNITED STATES PATENTS 2,863,752 12/1958 Harnm et a1.7l2.3 3,010,996 11/1961 Litvan et a1 260562 X FOREIGN PATENTS 2/1953Sweden.

LEWIS GOTTS, Primary Examiner.

JULIUS LEVITT, JAMES O. THOMAS, 111.,

Examiners.

1. A METHOD FOR PREVENTING PLANT GROWTH WHICH COMPRISES APPLYING TOSOILS NORMALLY SUPPORTING SAID GROWTH A GROWTH-INHIBITING AMOUNT OF ANA-HALOACETANILIDE OF THE FORMULA